68 lines
1.8 KiB
C++
68 lines
1.8 KiB
C++
#include "threadpool/atomic_helpers.h"
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#include <stdexcept>
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#ifdef USE_PTHREAD_ATOMIC_LOCK
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// Print a warning if we defaulted to use pthreads for atomic operations
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// This can decrease the performance of atomic operations
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// We print the message here so it is only printed once
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#warning using pthreads for atomic operations, this may affect performance
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#endif
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namespace AtomicOperations {
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#ifdef USE_PTHREAD_ATOMIC_LOCK
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pthread_mutex_t atomic_pthread_lock;
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static pthread_mutexattr_t threadpool_global_attr;
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static int create_atomic_pthread_lock()
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{
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pthread_mutexattr_init( &threadpool_global_attr );
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int error = pthread_mutex_init( &atomic_pthread_lock, &threadpool_global_attr );
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if ( error != 0 )
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throw std::logic_error( "Error initializing mutex:" );
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return error;
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}
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int atomic_pthread_lock_initialized = create_atomic_pthread_lock();
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#endif
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// Atomic operations for floating types
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double atomic_add( double volatile *x, double y )
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{
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static_assert( sizeof( double ) == sizeof( int64_atomic ), "Unexpected size" );
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union U {
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double d;
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int64_atomic i;
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};
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U a, b;
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bool swap = false;
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auto x2 = reinterpret_cast<int64_atomic volatile *>( x );
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while ( !swap ) {
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a.i = atomic_add( x2, 0 );
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b.d = a.d + y;
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swap = atomic_compare_and_swap( x2, a.i, b.i );
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}
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return b.d;
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}
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float atomic_add( float volatile *x, float y )
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{
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static_assert( sizeof( float ) == sizeof( int32_atomic ), "Unexpected size" );
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union U {
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float d;
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int32_atomic i;
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};
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U a, b;
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bool swap = false;
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auto x2 = reinterpret_cast<int32_atomic volatile *>( x );
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while ( !swap ) {
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a.i = atomic_add( x2, 0 );
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b.d = a.d + y;
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swap = atomic_compare_and_swap( x2, a.i, b.i );
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}
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return b.d;
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}
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} // AtomicOperations namespace
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